After my last update, vlc stopped working. I tried rolling back the vlc version as well as the updated packages. It still sigfaults on startup. I also removed a few KDE components, (kate, okular, ark, kdelibs) and their dependencies, however vlc wasn't built with USE=kde and didn't depend on any of the removed packages. I have vlc built like so:

There don't appear to be any major differences other than I am using -gnome and -udev. Since my build is crashing on startup before it can even do simple things like --version or --help, I seriously doubt that support for different features and codecs is used in the code and therefore the source of the sigfault.

However, I don't think that use flags are going to change anything. VLC was working for months and then stopped. I can't even run vlc --version anymore. I suspect either a bug somewhere and I would like to be able to make a report that doesn't waste everyones time.

However, I did manage to get some more useful output. Maybe someone sees something?

Yes there does seem to be a problem there. My laptop with a practically identical setup has that directory and file. I thought it was a simple check for plugins and a warning that it didn't find any._________________First things first, but not necessarily in that order.

So it segfaults in hand-written ASM...
Which version of glibc do you use? Which USE-Flags? CFLAGS? (emerge --info would be nice) What about your processor? (cat /proc/cupinfo)
Also the last emerged packages would be nice (qlop -l -> qlop comes with portage-utils), from the point you are sure vlc still worked fine (better more then less).

Did you already try running /usr/lib64/vlc/vlc-cache-gen yourself?
Does it fix the issue?
Probably the error is in this one specific plugin, so does USE="-svg" emerge vlc fix the issue? (Of course, if it does NOT crash anymore after running vlc-cache-gen and you want to check if it is only that plugin, remove plugins.dat, again)

EDIT: I am marking the thread as solved since the problem has been isolated enough to file a concise bug report. Thank you for your help._________________First things first, but not necessarily in that order.

From what franzf said, it sounds like someone tried to hand code some assembly. This may produced efficient code, but it doesn't seem to agree with my processors._________________First things first, but not necessarily in that order.

This sounds a lot like this bug. On my system, I too, can cleanly emerge vlc 2.0.7 by removing the SVG USE flag, but I'll get a segmentation fault when starting vlc. If I remove both the libnotify and svg USE flags, vlc 2.0.7 will emerge cleanly, and start, but when I select a video to play, it then segfaults, as I described in the bug report comment section. I can only use vlc 2.0.7 now, by removing the qt4 USE flag, (of course that means no GUI). In this instance vlc 2.0.7 emerges cleanly, and will actually play a video file using the command line version, cvlc, only. Note this is with both libnotify and svg USE flags enabled.

Interesting. In my case removing svg results in a perfectly usable build. It looks like we may have been hit by two sides of the same bug, although in my case vlc-cache-gen didn't sigfault._________________First things first, but not necessarily in that order.

Aiii, seems to boil down to an issue with glib >(=)2.35...:
https://bugs.gentoo.org/show_bug.cgi?id=405173#c32
As USE="-qt4" emerge vlc fixed at least vlc-cache-gen, probably the malicious part is inside qt4's glib support.
So just for a quick test, could you reemerge qtcore + qtgui with USE="-glib"? It might cry if you run kde or qtwebkit[+gstreamer], but for the sake of this issue it would be great if you could test this.

For the record:
Just installed vlc-2.0.7[svg, libnotify]. I am running the "malicious" glib-2.36.3-r1. vlc does NOT crash.

[edit] probably it is enough to rebuild qtcore+qtgui (+qtdbus?) after the glib update 2.34->2.36? [/edit]

1) with dev-libs/glib-2.36.3-r1 installed, force a re-emerge of dev-qt/qtcore-4.8.5 and dev-qt/qtgui-4.8.5 without the glib USE flag
2) emerge media-video/vlc-2.0.7 with my normal USE flags
3) media-video/vlc-2.0.7 emerges cleanly
4) running vlc from the GUI or command line, operates normally (finally)

As you may have expected, media-video/vlc-2.0.7 continued working correctly even after I downgraded back to dev-libs/glib-2.36.3. However, after re-emerging dev-qt/qtcore-4.8.5 and dev-qt/qtgui-4.8.5 with the glib USE flag enabled, media-video/vlc-2.0.7 continues working normally. Weird huh?

Thanks again. You're certainly closing in on the problem. It looks like it's a complicated bug, (or perhaps series of bugs), this time.

1) with dev-libs/glib-2.36.3-r1 installed, force a re-emerge of dev-qt/qtcore-4.8.5 and dev-qt/qtgui-4.8.5 without the glib USE flag
2) emerge media-video/vlc-2.0.7 with my normal USE flags
3) media-video/vlc-2.0.7 emerges cleanly
4) running vlc from the GUI or command line, operates normally (finally)

As you may have expected, media-video/vlc-2.0.7 continued working correctly even after I downgraded back to dev-libs/glib-2.36.3. However, after re-emerging dev-qt/qtcore-4.8.5 and dev-qt/qtgui-4.8.5 with the glib USE flag enabled, media-video/vlc-2.0.7 continues working normally. Weird huh?

I had the same problem, and I tried your last solution - but WITH the glib USE flag. It works, so that's probably why it continued to work for you too